That means we’ve been heading into days with less and less daylight—the highest risk period for seasonal affective disorder (SAD), also called seasonal depression or winter depression.

If you’ve experienced high levels of sadness, fatigue, irritation, agitation, sleep disruption, and similar symptoms of depression, especially if they’ve been worsening as December drags on, it’s not your imagination. SAD is very common, affecting an estimated 5% of adults in the US.  

The Diagnostic Manual of Mental Disorders (DSM-5) lists SAD as Major Depressive Disorder with Seasonal Pattern because it’s triggered by less daylight exposure. Many people who experience SAD may not realize it’s an actual condition because they don’t have depression symptoms throughout the year. According to the American Psychiatric Association, SAD lasts about 40% of the year.

SAD tends to affect women more than men. Unsurprisingly, the further you live from the Equator, the higher your risk of SAD because higher latitudes have less sunlight. It’s important to recognize the symptoms, whether in your patients, colleagues, friends, family, or yourself, so that you can address them.

Symptoms of SAD

SAD’s symptoms are the same ones you’d find for major depression, except that they tend to worsen as the days shorten:

• Feeling sad and depressed

• Losing interest in activities you used to enjoy

• Appetite changes, especially eating more or craving more carbohydrates

• Changes in sleeping habits, especially sleeping too much

• Weight gain

• Social withdrawal, such as feeling like you want to hibernate away from others

• Fatigue, sleepiness, or loss of energy despite getting enough sleep

• Increase in “purposeless activity,” such as pacing, handwringing, inability to sit still, etc., more than usual.

• Slowed movements or speech that others notice

• Feeling worthless or guilty

• Having trouble thinking, concentrating, focusing, or making decisions

• Thoughts about death or suicide

Treatment for SAD

A wide range of options are available to treat SAD, and combining multiple treatments is often helpful. Symptoms should improve on their own as the days grow longer, and there’s more daylight, but if symptoms are severe enough to interfere with daily functioning, it’s often more important to receive treatment than to wait it out.

Light Therapy

This therapy involves an upfront cost unless there are options for patients to rent a light therapy lamp. A light therapy lamp emits a very bright light that a person sits in front of for at least 20 minutes daily. The light is meant to replicate the effects of sunlight, though it does not contact harmful UV rays. If a patient plans to purchase a light therapy box, it’s important to do some research to find out which are highly rated. See the reviews at Wirecutter, Very Well Mind, and Health.

Light therapy, like most treatments for depression, does not work immediately. Most people start feeling better about one to two weeks after starting treatment, but they must sit in front of the light daily. Once they begin feeling better, it’s important to continue therapy each day throughout the winter to avoid relapse.

Talk Therapy

Cognitive behavior therapy is one of the most effective forms of psychotherapy and is particularly effective at treating SAD.

Vitamin D

Since we get much of our vitamin D from sunlight, sometimes a vitamin D deficiency may contribute to SAD. Testing vitamin D levels can reveal whether you have low levels and could benefit from a daily supplement.

Increased Sunlight Exposure

While this seems like an obvious treatment, it’s not necessarily available to everyone, depending on their geography and lifestyle. For example, people who work in a windowless office, especially if it’s dark when they commute to work and already dark when heading home, may not have many opportunities to spend time in the sun. Regardless, spending time in the sun when you can is another way to treat symptoms of SAD. This could involve sitting outside during lunch hour, sitting close to a window during the day, or spending more time outdoors on the weekends. Exercising out in the sun is even better since exercise can help treat depression. As always, protect yourself to reduce the risk of sunburn and skin cancer.  

Antidepressant Medication

Selective serotonin reuptake inhibitors (SSRIs) can treat SAD just as they’re used to treat other forms of depression. Some people may wish to avoid these unless other therapies don’t work because they’re only needed seasonally. Since it takes a few weeks for them to begin working and it can take several weeks to wean off them, which can also involve withdrawal symptoms, antidepressants may be a less efficient option until they’re the only ones left.